go to start - run
type %temp%
delete all the files
restart the symantec servcies, log in and check , should be fine.

Deleted all of the files, still the same situation. Tried restarting the machine as well after the files were wiped, still no luck.

is this a fresh install?
can you try uninstall /reinstall?
You installed it on C drive or diff drive? 

Yes it is a fresh install. This morning I uninstalled/rebooted/reinstalled. The machine is an XP SP3 and it is installed on the C: drive.

We currently use Endpoint Protection on our machines for anti virus, which was removed some time ago on this box. I had removed alot of registry keys, and possibly ran a tool I found on the website for removal (can't remember 100% if one exited for Symantec or not). Although this has been done for quite some time, I'm thinking maybe the two could be related?

Are there any log files / debugging utilities I can run to try to pinpoint this?

in temp folder you should find the file called
scm- ui.err file ( is it 0 kb) 
check the scm-server 0.log found under
C:\Program Files\Symantec\Symantec Endpoint Protection Manager\tomcat\logs

Let me back track a second as I'm still going through the guides. Forgive me because we're currently evaluating 5-6 different products for centralized administration..

-I've downloaded the Small Business package, Symantec_Endpoint_Protection_Small_Business_Edition_12.0.1_AllWin_EN_TW.zip.
-Unzipped and ran the setup.exe file
-Went through the installation without any errors
-Received the error when logging in for the first time
-Uploaded my temporary license file

So the error message keeps popping up when I try to do "Add a computer". Do i need additional software to perform this? My guess is that it should be packaged within the zip, and that it is already on the management machine.

Thanks for the input, I'll have a look at the files and report back.

you dont need any other software, try running the management server configuration wizard,